The purpose of this application is to acquire a mass spectrometer, specifically the TSQ Vantage Triple Stage Quadrupole instrument from Thermo Scientific. The TSQ Vantage has unique capabilities to support ongoing studies that investigate pathophysiological pathways of diverse medical illnesses as well as programs that are developing novel therapeutics. This instrument will be used exclusively for quantitative proteomic applications by 10 NIH funded investigators located primarily at the Translational Research Laboratories (TRL) in the University of Pennsylvania. Ongoing projects initiated by these investigators have employed genomic discovery, biochemical, and molecular approaches to discover proteins of interest, posttranslational modifications, and protein networks that execute biological functions. The majority of these projects have advanced past the stages of discovery and specific and practical protein and peptide targets have been identified. A critical next step for these projects is to explore these discoveries in depth by quantifying changes in proteins and peptides that occur in various diseases or treatments. This goal cannot be accomplished with typical antibody based western blot, ELISA or even with currently available linear ion trap mass spectrometers due to lack of sensitivity, specificity, and/or high throughput of these approaches. Targeted peptide quantification is a highly selective and sensitive methodological approach for quantitative evaluation of dynamic changes of proteins and protein networks as well as the validation and utilization of biological markers. Towards this goal the PI and the users of the proposed instrument, have developed and established methodologies that employ stable isotope labeled peptides, proteomes and multiple reaction monitoring (MRM)/mass spectrometry (MS) workflows for the quantification of proteins in human samples and animal and cellular model systems. A TSQ Vantage unit (Thermo-Scientific) combined with an Eksigent Nano 2DLC, which has been operational in the TRL since September 2010, will remain until March 2013 on a lease supported by the University of Pennsylvania. We propose to acquire this remarkably productive unit. Chang-Gyu Hahn, M.D, Ph.D. as the P.I will assume overall responsibility for the equipment. Leadership will be equally divided between Chang-Gyu Hahn, M.D, Ph.D. and Ian Blair, Ph.D. Functioning as Co-P.I.'s. Dr. Hahn will focus on the operational aspects and Dr. Blair will provide scientific oversight.